Simple Interest
Math MCQs

Question :    Calculate the amount due if Joseph borrowed a sum of $3700 at 10% simple interest for 3 years.

Correct Answer  $4810

Solution & Explanation

Solution

Given,

Principal (P) = $3700

Rate of Simple Interest (SI) = 10%

Time (t) = 3 years

Thus, Amount (A) = ?

The Rate of Interest is always calculated per annum, i.e. per year.

Thus, here 10% simple interest means, Rate of Simple Interest (SI) is 10% per annum.

Method (1) Using Formula

Calculation of Simple Interest

Formula to Calculate Simple Interest

Simple Interest (SI) = Principal × Rate × Time

Thus, Simple Interest (SI) = $3700 × 10% × 3

= $3700 ×¹⁰/₁₀₀ × 3

= ^{3700 × 10 × 3}/₁₀₀

= ^{37000 × 3}/₁₀₀

= ¹¹¹⁰⁰⁰/₁₀₀

= $1110

Thus, Simple Interest = $1110

Calculation of Amount

The total money paid to the lender by a borrower is called the Amount.

In other words, sum of priciple and interest is called the Amount.

Formula to Calculate the Amount

Amount = Principal + Interest

Thus, Amount = $3700 + $1110

= $4810

Thus, Amount to be paid = $4810 Answer

Method (2)

Calculation of Amount when Principal, Rate of Simple Interest and Time are given

Calculation of Amount directly using Principal, SI, and Time

Formula to calculate the Amount

Amount (A) = Principal (P) + Principal(P) × Rate of Interest (SI) × Time (t)

⇒ A = P + PRT

Here in the question, P = $3700

Rate of Simple Interest (SI) or (R) = 10%

And, Time (t) = 3 years

Thus, Amount (A)

= $3700 + ($3700 × 10% × 3)

= $3700 + ($3700 ×¹⁰/₁₀₀ × 3)

= $3700 + (^{3700 × 10 × 3}/₁₀₀)

= $3700 + (^{37000 × 3}/₁₀₀)

= $3700 + (¹¹¹⁰⁰⁰/₁₀₀)

= $3700 + $1110 = $4810

Thus, Amount (A) to be paid = $4810 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 10%

This, means, $10 per $100 per year

∵ For $100, the simple interest for 1 year = $10

∴ For $1, the simple interest for 1 year = ¹⁰/₁₀₀

∴ For $3700, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3700

= ^{10 × 3700}/₁₀₀

= ³⁷⁰⁰⁰/₁₀₀ = $370

Thus, simple interest for 1 year = $370

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $370 × 3 = $1110

Thus, Simple Interest (SI) = $1110

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3700 + $1110

= $4810

Thus, Amount to be paid = $4810 Answer

Similar Questions

(1) In how much time a principal of $3200 will amount to $4000 at a simple interest of 5% per annum?

(2) Calculate the amount due after 9 years if Mary borrowed a sum of $5050 at a rate of 3% simple interest.

(3) What amount does Linda have to pay after 5 years if he takes a loan of $3350 at 8% simple interest?

(4) Daniel took a loan of $6200 at the rate of 7% simple interest per annum. If he paid an amount of $9238 to clear the loan, then find the time period of the loan.

(5) Calculate the amount due if Barbara borrowed a sum of $3550 at 4% simple interest for 4 years.

(6) David took a loan of $4800 at the rate of 10% simple interest per annum. If he paid an amount of $9600 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due after 10 years if John borrowed a sum of $5200 at a rate of 3% simple interest.

(8) What amount does Christopher have to pay after 6 years if he takes a loan of $4000 at 9% simple interest?

(9) Calculate the amount due after 10 years if David borrowed a sum of $5400 at a rate of 8% simple interest.

(10) Find the amount to be paid if Linda borrowed a sum of $5350 at 9% simple interest for 8 years.